What are Geotechnical Sensors?

What are Geotechnical Sensors?

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By Shane Garcia

Structures have individual foundation designs, but the variable nature of transparent soil and rocks spawns the need for geotechnical monitoring and testing. Extensive monitoring is necessary pre and post-construction to enhance the safety and integrity of the structures.

Geotechnical monitoring begins with surveying the construction land and peripheral areas until the structure is fully set up. You might be wondering what geotechnical monitoring is and how it is done. The article provides an in-depth overview of the concept.

What is Geotechnical Monitoring?

Geotechnical monitoring is the continuous evaluation of the ground’s performance against a proposed construction. Engineers use geological sensors to determine if the structure needs adjustments to enhance stability during and after construction.

Statutory authorities also require engineers to perform geotechnical monitoring before undertaking large projects near populated areas or involving sensitive geological structures. The process involves tracking ground and structural movements, water pressure, and vibrations.

Benefits of Geotechnical Monitoring

Structures collapse due to geological instability, design error, and deterioration of construction materials, among other reasons. Effective geotechnical monitoring prevents such failures by providing critical information regarding:

Construction Stage

During construction, geotechnical monitoring helps:

• Verify the design’s hypotheses and assumptions
• Ensure safety during construction
• Verify the performance of the new structure
• Make the necessary parameter changes
• Ensure the structure’s interface aligns with any adjacent structures and their foundations

After Construction

Geotechnical monitoring is necessary after construction to:

• Ensure the structure is safe for use for the long-haul
• Compare and identify variances between the initial design assumptions and observed data
• Evaluate the implication of structural activity on parameters like pressure, deflection, stress, water, inclination, and stress

Geotechnical Instrumentation

This is a critical aspect of any construction monitoring process as it provides essential information about the structure’s performance and detects problems early. The scope of geotechnical engineering depends on the structure’s complexity and the potential loss of adjacent properties and life.

Different tools called geological sensors are used in the instrumentation process to measure groundwater level, lateral movement, pore pressure, stress, temperature, deformation and water flow. The most common geotechnical instruments include:

Piezometers

Piezometers are geotechnical sensors used to measure pore water pressure. Water pressure is critical when undertaking major civil engineering projects like dams, high-rise buildings, and tunnels. The pressure builds up when water accumulates in the pores of rocks, earth materials, or concrete structures. Piezometers also come in handy when drilling boreholes, where they are used to monitor the groundwater.

Inclinometers

This is a transducer that determines the extent of deformation of a structure. It’s often used to measure the performance of excavation support systems during the construction and excavation of structures in slope failure zones. The inclination angle is presented as a percentage or in degrees relative to gravity.

Traditional inclinometer systems include a manual probe, cable and cable reel, and a data collection readout. However, case studies have shown a range of limitations with traditional inclinometers, including reading errors leading to the development of inclinometers with optic sensors. They are more cost-effective and can monitor many measurement arrays.

Tilt Meters

They are similar to inclinometers, except they measure sensitive structures to identify small changes at a vertical level. Tilt meters are attached to the structures and changes in the tilt of the wall are presented in a schematic diagram.

Total Stations

They’re used for positional monitoring when measuring excavation support systems, settling fills, and measuring infrastructure movements. Total stations can be manually operated or use measurement automation platforms to support data gathering in a wide range of settings effortlessly.

Strain Gauges

The sensors measure stress or strain in underground tunnels, bridges, cavities and concrete or masonry dams. In order to measure stress, the gauge is attached to the object with adhesive. Strain gauges consist of flexible sensors with an insulating foil backing to ensure they’re sensitive to the slightest strains.

Load Cells

This is another type of transducer used to convert force into quantifiable electrical output. Load cells are only effective when paired with an external sensor like a strain gauge.

Data Loggers

Also referred to as data recorders, they are battery-operated instruments that provide real-time data from different geotechnical sensors and present them in a readable format. Data loggers aid structural health monitoring by providing critical parameters like a structure’s water level, pressure, stress, temperature, and strain.

Temperature Sensor

The device measures the weight or cold of an object. The extent of temperature change is directly proportional to the tip resistance. Thus if an object is cold, there is lesser resistance. In geotechnical applications, temperature sensors measure the internal temperature of structures like buildings, bridges, power plants, and dams.

Shane Garcia

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3 Thames Street BOLTON, BL1 6NN

01204 456413

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